The present invention is directed to a device for fastening a die on a cylindrical tool carrier of a rotary machine, which may be a box board converting machine.
In order to reduce, as much as possible, the lack of positioning precisions of a processing tool and also to render changes of such tool easier when passing from one production run to another, professionals customarily fit these tools previously on a die which is thereupon transferred onto a cylindrical tool carrier which might be the upper cylinder. A lower cylinder would then be provided with an elastomer tape or coating. With the cylinders rotating at a high speed and in full synchronization, the pair of cylinders will carry a processible workpiece forward and process the workpiece simultaneously.
Such a die appears in the form of a cylindrical portion or shell, for example a wooden one, cut into pieces according to a precise pattern, and the configuration of the tools have to be fitted on these dies. The term "inner front face of the die" means the underlying face turned toward the axis of rotation of the cylindrical tool carrier. Such a processing tool can then be inserted into apertures of the die until their base reaches the level of the inner aperture configuration and the upper and active tool parts protrude, then, from an outer front face of the die.
With the present state of the art, a tool carrier cylinder has a screen-like network of tapped apertures allowing the fastening of the die onto the cylinder by threaded fasteners, such as screws. Considering the high speed of rotation for the cylinder, as well as the non-negligible weight of the dies provided with the processing tools, the centrifugal forces arising at the level of the die are considerable and have a tendency to tear the die from the cylinder. In consideration of this technique, such a die will, therefore, have to be screwed on at numerous points. Thus, during a die change, this will necessitate a long machine down time. Moreover, as every screw has to be tightened individually, it cannot be excluded that one or several of these screws might be accidentally omitted and, thus, the process of changing dies includes a lengthy and fastidious checking at the end of the job to avoid any accidents due to improper securing of the die on the cylinder.